In the United States and many other industrialized countries the problem of solid waste disposal is reaching crisis proportions. A strong demand for new technologies, strategies, and materials that offer less environmentally harmful alternatives to past practices is needed. One approach to decrease the growth rate of landfills is to enhance the biodegradability of its constituent materials. As these items degrade in a landfill, they will occupy less space and allow more material to be placed in the site. A problem with this strategy is that landfills, designed to be stable systems, tend to suppress efficient physical and biological decay.
Another approach is to compost biodegradable materials at a separate site, thereby reducing the amount of waste going to the landfill from the outset. The end product of composting can be used in a variety of manners including use in lawn and garden applications. The viability of this alternative is directly dependent on the time required for sufficient biodegradation of the substrate. While paper is biodegradable under favorable conditions, the rates may be so slow that composting or biodegradation in a landfill results in no practical benefit.
Paper and paperboard, which are major contributors to the solid waste stream, are composed primarily of cellulose, a compound that lacks the nutrients essential for the proliferation of many types of saprophytic microorganisms. Saprophytic microorganisms are found in the air, soil or water and aid in the decomposition of dead or decaying plants and animals. Generally, cellulose degrades at a more rapid rate as compared to items such as plastics, synthetic fibers and other man-made materials, but the breakdown rate is too slow to result in rapid decomposition in a compost environment.
Biodegradable paper products are known in the prior art.
U.S. Pat. No. 3,645,769 to Willey et al., discloses a disposable toilet tissue impregnated with viable yeast to induce promotion of bacterial growth in septic tanks. The yeast is added onto the finished paper in either a powder or liquified form and dried.
U S. Pat. Nos. 3,647,111 and 3,800,977 to Stager, disclose a container that deteriorates after prolonged exposure to moisture and oxygen with the aid of biological agents. The biodegradable material is a laminate having an inner organic filler material layer comprising peat, wood, flour, cotton, linen or other fibrous organic material sandwiched between two outer layers comprised of a phenolic resin with a metallic salt of a fatty acid.
However, the prior art has not shown the production of biodegradable paper products which coat chemical nutrients on a paper product or incorporate chemical nutrients into the manufacture of a paper product to enhance microbial activity and thus enhance its biodegradability.
An article in the Wochenblatt fuer Papierfabrikation journal dated Jan. 30, 1984, discloses the use of microorganism control in the recycling of paper products. Biodegradable organic materials such as starch, nitrogen, phosphate, sulphate, nitrate, calcium and magnesium salts are contained in the process water and used as nutrient sources by anaerobic microorganisms to control the problems of slime, odor and corrosion during the manufacture of paper products. This reference, however, does not disclose methods for coating chemical nutrients on a paper product or incorporating chemical nutrients in the manufacture of a paper product to enhance microbial activity and thus enhancing its biodegradability.
There is a need in the art for processes which enhance the biodegradability of paper products. This invention is directed to provision of such processes which have diverse applications in curbing the solid waste crisis. It will be appreciated that advantage would be obtained by providing methods for the enhancement of the biodegradability of paper in a litter situation which would provide numerous societal benefits. A means of ensuring and enhancing the rate of biodegradability of paper and paperboard waste components will allow treatment of these materials differently than taking up valuable landfill space.
Accordingly, it is a broad object of the invention to enhance the rate of biodegradability of paper and paperboard by treating such paper or paperboard with chemical solutions, having properties which increase the decomposition of the paper fiber constituents, such that the chemical solutions are absorbed and retained by the paper or paperboard. Alternatively, the chemical solutions are incorporated into a fibrous slurry and formed into such paper or paperboard using paper making apparatus.
A more specific object of the invention is to provide a method which enhances the biodegradability of paper and paperboard by treating such paper or paperboard with chemical solutions which are a source of alternate electron acceptors for facultative anaerobic decomposition of the paper or paperboard.
Another object of the invention is to provide a method which enhances the biodegradability of paper and paperboard by treating such paper or paperboard with chemical solutions which are nutrient chemicals that increase microbial growth on the paper or paperboard.
A further object of the invention is to provide a method which enhances the biodegradability of paper and paperboard while retaining the strength and flexibility of the untreated paper.
A further specific object of the invention is to provide a method for producing biodegradable paper which is less complex and improved over the prior art.